The 2003 invasion of Iraq and subsequent instability led to the death of 150,000 Iraqis and 179 British troops, and severe injuries to many more.

British families whose sons and daughters served in the war have also had it confirmed today that troops were inadequately equipped for battle.

For bereaved families living in Yorkshire and elsewhere in the UK they have endured an agonizing seven year wait for the report’s release and the reasons why Mr Blair supported the US led invasion and committed British troops.

There is likely to be disappointment the report does not make a judgement on the legailty of the war, but fresh weight is given to the belief that decisions were not made in an acceptable way.

Sir John said: “The inquiry has not expressed a view on whether military action was legal. That could, of course, only be resolved by a properly constituted and internationally recognised court.”

“We have however, concluded that the circumstances in which it was decided that there was a legal basis for UK military action were far from satisfactory.”

The decision making process that disregarded the UN Security Council’s lack of support for action was also criticised, and the UK accused of undermining the council’s authority.

The report reveals that both the military and civil service both asked whether force would be legal, but the then attorney general Lord Goldsmith advised that “on balance” there was a secure legal basis for military action without a further Security Council resolution.

“Given the gravity of the decision, Lord Goldsmith should have been asked to provide written advice explaining how, in the absence of a majority in the Security Council, Mr Blair could take that decision.

“This is one of a number of occasions identified by the inquiry when the policy should have been considered by a Cabinet Committee and then discussed by Cabinet itself,” said Sir John.

The negative consequences of a very small number of people making key decisions and the lack of collective ministerial responsibility is one of the lessons that must be learnt from the inquiry, he concluded.

The long-disputed threat of Iraq’s weapons of mass destruction are also laid bare in the report.

If finds that the Joint Intelligence Committee should have made clear to Mr Blair that the assessed intelligence had not established “beyond doubt” either that Iraq had continued to produce chemical and biological weapons or that efforts to develop nuclear weapons continued.

The report concludes that in 2003, there was no imminent threat from Saddam Hussein and the strategy of containing the Hussein regime could have continued for some time.

The much discussed “special relationship” between the UK and US is also drawn into sharp focus with the humiliating conclusion that Mr Blair had over-estimated his ability to influence US decisions on Iraq.

When the two countries disagree on issues of foreign policy they should be bold enough to do so , said Sir John.

“The UK’s relationship with the US has proved strong enough over time to bear the weight of honest disagreement. It does not require unconditional support where our interests or judgements differ.”

Equipment concerns that dominated the headlines in the early days of the war will make for difficult reading for families who have long suspected their loved ones were not adequately protected.

Sir John said: “We have found that the Ministry of Defence was slow in responding to the threat from Improvised Explosive Devices and that delays in providing adequate medium weight protected patrol vehicles should not have been tolerated.

“It was not clear which person or department within the Ministry of Defence was responsible for identifying and articulating such capability gaps. But it should have been.”

The management of the post-invasion era was also a significant failing with the Blair administration described as unable to stabilise, administer and reconstruct Iraq.

They did not accept the evidence given by Mr Blair that he could not forsee the “risks of internal strife” in Iraq, active Iranian pursuit of its interests and regional instability.

“The UK military role in Iraq ended a very long way from success,” said Sir John.

He described the invasion as having gone “badly wrong, with consequences to this day.”

Concluding his statement, he said: “Above all, the lesson is that all aspects of any intervention need to be calculated, debated and challenged with the utmost rigour. And, when decisions have been made, they need to be implemented fully.

“Sadly, neither was the case in relation to the UK Government’s actions in Iraq.”